Dry mixes for use in electrolytic recording



Patented June 3, 1948 in!) STATES PATENT DRY MIXES FOR USE INELEOTROEY TIC RECORDING Harold-G. Greig, PrincetomfN. .1., assign'or to Radio Corporation of America, acorporation' of Delaware NoDrawing. ADDIicationNovemberA, 1944 Serial No. 562,032

17 Claims.

chloride, potassium chloride and the like-and'a coupler, is disclosed in Solomon U. S. P. 2,306,471. In my copending application, Serial No'. 562,033, filed of even date herewith and entitled Electrolytic recording, it is suggested thatthere be substituted for the amine and nitrite of such solution a stabilized diazo amino compound. Manifold advantages, including an improved stability of the records to light, are obtained when operating in this way. It has been found'that these two methods are the most eflicacious'for electrolytically producing color image records especially in facsimile recording. By the term facsimile recording as used herein is meant not only the reproduction on the receiver of-a preexisting subject, but also the reception of subject-matter in the process of creation'or formation.

The production from dry mixesof the electrolytic recording solutions with which the receiver is treated in these methods has-manifest advantages. If the dry mix be storage stable, itcan be prepared in bulk and stored for aconsiderable period of time. Furthermore, it can be shipped to whatever destination desired at a much-lower cost than the water solutions. The production of dry mixes suitable for use in these processes has accordingly been a desiredatum in this art.

The couplers which have been found .toegive best results in the methods previously outlined are napthol sulfonic acids, of which chromotropic acid is an example. This acid is usually sold in the form of its mono-sodium salt. This salt is acid and if incorporatedinto a. dry-mix containing a diazotizable amine and anitriteor a stabilizeddiazo amino compound, it would induce premature diazotization and coupling in the first instance, and premature splitting of the diazo amino compound and coupling in the second instance. If, on the other hand, the alkalinity of such compounds be increased to :avoid such premature action by the'utilization of the usual alkalies such as sodium hydroxide, sodium carbonate, potassium hydroxide, andthelikait' is found .that the records obtained suffer because of a poor shade oftheimages. andbecause'of the instability of the background to'light. It has therefore been considered preferable, up toJthe present time,'to prepare fresh solutions'for electrolytic recording rather than to .produce' dry mixes which can be stored and shippedfonuseat a time in" the futuredespitethe advantages inherent in the latter course of action.

'Ihave now 'discover'ed'that the objections to .the dry mixes which has been previously, proposed can be avoided'by utilizing aslthetcoupling compoundin suchdry mixes a naphthol sulfonic acid,

either monoor poly-, in which at least one of the sulfonicacid groups is neutralized by mor- ,pho'line.

The morpholineiorms ;a salt of the naphthol sulfonic acids. 'Such salts .are stable and dissolve in water in the concentrations iii which they are used-in electrolytic recor'dingto givea 15H of approXimatlyQifi. .The alkalinity induced .by using the morpholine prevails-during storage so that noopremature' dia'zotization'or splitting of'the 'diazo amino compound with'resulting coupling takes place. 'Due'tothe stab'ility of such salts or to some other as .yet unascertained property thereof, solutions in water or an- .other suitable-solvent such as alcohol of dry mixes containing said salts, produce on electrolysis,.darkimage records the background of which hasamuch higherpermanence tolight than records obtained where the alkalinity has been produced by resort to the .usualalka'lies.

It is accordingly an objectiof my inventionto produce dry mixes for the production of electrolytic recording solutions whereinlthecoupling component is a naphthol su-lfonica'cid'in which at least one sulfonic acid group'ha's been neutralized by morpholine.

'It is a further object of my invention to produce dry mlixesfor the, production of electrolytic recording solutions wherein the coupling compoun'd'is a naphtholpolysulforiic acid in which at least one sulfonic acid group has'been neutralized by morpholine.

'It is a .furtherobject ofmy'in'vention topro- .duce storage stableldry mixes containing apri- .mary' aromatic amine, a .nitrite, an electrolyte and a naphthol sulfonic acid as the coupling-comwhich a sulfonic acid group has been neutralized by morpholine. It is a further object of my invention to produce dry mixes for forming electrolytic recording solutions in which the coupling compound is chromptropic acid, the sulionic acid groups of which have been neutralized by morpholine.

It is a further object of my invention to produce dry mixes for electrolytic recording solu- As the coupling component there may be used any naphthol sulfonic acid at least one sulto group of which has been neutralized by morpholine. Such compounds have the following formulae:

4 wherein n is 1 or 2, m is l to 3 and R is hydrotions in which the coupling compound is chromotropic acid, the two sulfonic acid groups of which have been neutralized by morpholine.

Further objects of my invention will appear as the description proceeds.

It has been stated that the dry mixes of the present invention contain either a diazotizable amine and a nitrite or a stabilized diazo amino compound. In other words, the diazonium ions which react with the coupling component have their origin in the diazotizable amine and a nitrite on the one hand, or a stable diazo amino compound on the other hand, and accordingly the term source of diazonium ions as used in the claims should be so construed. The diazotizable amine or the aryl amine from which the stabilized diazo amino compound is produced may be any of the diazotizable aryl amines utilized in the azo dyestuff art. Examples of suchamines are given in the aforesaid Solomon patent and in my copending application, Serial No. 562,033, filed of even date herewith and entitled Electrolytic recording, to which attention is directed. Such amines are, for example, naphthionic acid, 4.4- diaminodipheny1-2.2'-disulfonic acid, 4.4-diaminodiphenyl 3.3'-disulfonic acid, 4.4'-diaminodiphenylamine-Z-sulionic acid, orthotolidine-2.2'-

disulfonic acid, alpha-niaphthylamine-4.8-disulionic acid, alpha-naphthylanfine-S-sulionic acid, o-anisidine-4-sulfomc acid, and the like. These amines when used in the form of the stabilized diazo amino compounds may have their diazonium compounds stabilized with an aliphatic amine such as ethanolamine, diethanolamine, sarcosine, diisopropanolamine, dimethylamine, diethylamine and the like, by an aromatic amine which does not readily couple, such as 4-sulfo-2- aminobenzoic acid, 2-methylamino-4-suliobenzoic acid and the like, or by a heterocyclic amine, such as alpha-carboxy pyrrolidine, alpha-l-alpha-2-dicarboxy pyrrolidine, piperidine, carbazole and the like.

The stabilized diazo amino compounds are prepared by diazotizing the primary aromatic amine and reacting the resulting diazonium compound in an alkaline solution with one of the aforesaid organic amines which does not easily couple to form an azo dye. It is advisable when producing the stabilized compound, to use an excess of the stabilizing amine over the quantity theroretically necessary to produce the stabilized diazonium compound since otherwise difliculties may be encountered in the stability of the records to light.

gen or a substituent group, such as, amino, acetyl amino and the like. As examples of such naphthols, the morpholine salts of which are contemplated by the present invention, may be mentioned 2-naphthol-6-sulfonic acid 2-naphthol-8-sulfonic acid l-hydroxy-S-acetylamino naphthalene-3.6-disultonic acid 1 hydroxy-8-amino naphthalene-3.5-disulfonic acid 1-hydroxy-8-amino naphthalene 6.7-disulfonic acid 1.8-dihydroxynaphthalene-3.6-disulfonic acid 1-hydroxy-8-amino naphthalene-3.6 disulfonic acid l-hydroxy naphthalene-3.6-disulfonic acid Z-hydroxy-naphthalene-3.6-disulfonic acid.

1.7-dihydroxy naphthalene-3.6-disu1fonic acid 2-hydroxynaphthalene-6.8-disulfonic acid l-hydroxynaphthalene-3.6.8-trisulfonic acid 1.B-dihydroxynaphthalene-5.7-disulionic acid 1.5-dihydroxy-naphthalene-2.V-disulfonic acid 1.5-dihydroxynaphthalene-3.7-disulfonic acid 1.7-dihydroxynaphthalene-3.6-disulfonic acid 1 hydroxy-Z-aminc naphthalene-3.6-disulfonic acid and the like. Best results, however, have been secured with the salts of chromotropic acid and the use of the salt of this acid represents the preferred embodiment of my invention.

The preparation of the morpholine derivative of the coupling compound may be carled out in various ways. salt-say, of chromotropic acid-is desired, 1 mol of the mono-sodium salt of chromotropic acid is slurried with sufficient morpholine in excess of 2 mols to give a smooth, uniformly wet paste. The excess morpholine is then removed by drying at a temperature of about 65 to 70 C. As an alternative, 1 mol of chromotropic acid itself is reacted with 2 mols of morpholine at room temperature in a closed vessel, for instance, a ball mill, by means of which thorough mixing of the reactants can be accomplished. The morpholine is sufliciently volatile so that any excess over that which combines with the coupling agent is readily driven off at the temperatures of 65 to 70 C. referred to above.

It has been previously pointed out that at least one of the sulfonic acid groups of the coupling component is neutralized by morpholine.

'If the naphthol sulfonic acid employed is a monosulfonic acid, only the monoamine salt is formed, in which case the preparation is effected by using 1 mol of the naphthol sulfonic acid with For instance, if the morpholine air-least 1 molof morpholine. Where the couplingr component is-a polysulfonic acid-the ratio of the' reactants will vary dependmg-uponthe particularnaphthol olysulfonic acid selected and the results desired. If, for instance, a-disulfonic acid such as chromotropic acid is-used, a monoamine salt may be prepared by using 1 molof the sulfonic acid for each mol of morpholine. If, however, the di-salt is desired, at least 2 molsof morpholine are used for each mol of the chromotropic acid. Thus the gain in weight when slurrying the monosodium salt of chromotropic acid with a large excess of-morpholine and-drying, leadsto a product containing 2 mols of morpholine and 1 mol of chromotropicacid. Similarly, if the-polysulfonic acid isa trisulfonic acid, by adjusting the proportions in the'manner noted, themono-, dior triamine salt maybe produced.

It is also possible to produce salts of the naphthol polysulfonicacids in which one sulfonic acid group is-neutralized with morpholine and another group. is neutralized by means of an alkali metal. --It is thus possible when starting with 1 mol of the mono-sodium salt of chromotropic acid and treating the same with 1 mol of morpholine to obtain a mixed sodium-morpholine saltJ Again, by operating as indicated above, that is, by using a naphthalene disulfonic acid such .as chromotropic acid, with 1 mol of an alkylolamine and 1 mol of morpholine, it is possibleto prepare the mixed alkylolamine-morpholine salt.

The dry mixture which is used, irrespective of the source of the diazonium compound, must contain an electrolyte. The electrolyte is preferably sodium chloride, although other common electrolytes such as potassium chloride, sodium bromide and the like may be utilized with equally good results.

The preferred pH of the solution resulting from dissolving the dry mixture in water is between 9.5 and 11.5. In some instances, the alkalinity aiiorded by the salt of the coupling agent will not give the pH which is optimum for the component used. In that case, it is desirable to add a very small amount of an inorganic alkali such as-sodium hydroxide, potassium hydroxide or'the like. The quantity of this agent required will usually be from 1 to 2 grams per'liter of' the recording solution.

Other-ingredients may be incorporated 'in the dry'mix and-in particular a wetting agent to facilitate the impregnation of the carrier by the solution. Suitable wetting agents are sarcosin'es or ta'urines, the nitrogen atornof which is acylated'with a high molecular weight fatty acid such as oleic, palmitic, or the like, alkyl naphthalene sulfonic acids, such-as butyl naphthalene-sulfonate, and the like, and the condensation product of a sulfonated benzene with chlorinated kerosene, said condensation product having the-formula:

SOaNa whereinR represents the hydrocarbon radicals Theinvention will be further understood from the following examples, but it-isto'be -remem JIS Example I .2 gram-mol of the-mono-sodium saltv of chromotropic acid in the form of a finely ground dry powder isslurried with 1.1 gram molsof morpholine un-til a smooth, thick-paste is obtained. This paste is stirred atroomtemperature until the mass has become uniform and thoroughlywet throughout. The excess morpholine is then driven oil by heating the composition to a temperature of 65-70'C. The product thus obtained is then ground for further-use. When dissolved in water in the ratio of .03- gram mol per liter, itgives a solution of a pH of about 9.5.

.2 gram mol of said morpholine salt of chro-- motropic acid, .4 gram mol-of the diazo compound from diazotized naphthionic acid and diethanolamine; 3.3 'gramsof-the condensation product of benzene-sulfonicacid with chlorinatedkerosene, 163.8 grams of sodium chloride; and 8.2 grams of sodium hydroxide are thoroughly ground and mixed together to produce a uniform dry'product,

' 74.5 gramsofthi's' mixture are dissolved in a liter of water for'the preparation of afacsimile recording solution. This solution has a DH of 10.1. Records produced with such a solution are a dark blue purple, the background of which has a high stability to light;'

The diazo amino compound from diazotized naphthionic 'acid and dithanolamine referred to above isobtained as follows:

.5 gram molof sodium naphthionate are dis solved in approximately 750 cc. of water to which sufficient sodium hydroxide is added to make the solution alkaline to brilliant yellow test paper.

.5 gram mol of sodium nitrite is then added and the solution isrun under rapid agitation at a temperature 0f'5 to 10 0. into a solution of 140 cc. of 38% hydrochloric acid' and 75000; of water and ice. Diazotization is complete almost as soon as the solution is added and the diazonium compound, which is quiteinsoluble, precipitates out as a thick creamy slurry. Stirring is continued for one hour to obtain the product in a form in which it is more easily filtered.

The filter cake obtained upon filtration is reslurried in approximately 500 cc. of Water until a smooth paste is obtained. This paste is added slowly at 10 to 15 C. over a two-hour period with rapid agitation'to a solution of cc. of diethanolamine in 25000. of water while maintaining a temperature of 10 to 15 C. in an ice bath to minimize decomposition.

The reaction is complete when all the diazoniumium compound has been added. The resulting solution'is amber in'color and may stain paper with a reddish tint. It must be alkaline when tested with brilliant yellow 'test'solution.

2 grams of sodium hydrosulfiteare added and the solution stirred for one-hour at-room temperature to clear away the red-staining impurities. 20 grams of activated charcoal are incorporated and'the temperature raised to 50 to 55 C. for-V2 hour for the purpose of further clarifying the solution and to remove basic impurities. Thesolution is then filtered and the volumeis adjusted to 100000.

solved in .574 gram mol of morpholine .IOfgram Example III The procedure is the same as in Example I except that the chromotropic acid is replaced by 1 hydroxy-8-amino-naphthalene-6.7-disulfonic acid.

Example IV The procedure is the same as in Example except that the chromotropic acid is replaced by 2-hydroxy-naphthalene-3.6-disulfonic acid.

Example V The procdure is the same as in Example I except that the chromotropic acid is replaced by 1.7-dihydroxynaphthalene-3.6- disulfonic acid.

Example VI .03 gram mol of sodium naphthionate, .02 gram mol of sodium nitrite, 1. gram mol of sodium chloride, and .015 gram mol of the chromotropic acid-morpholine salt of Example I are thoroughly ground and mixed together to produce a uniform product. To the mixture there is added a small amount of sodium hydroxide approximating 1 gram. 7

The above dry mixture is stable and will remain so for a prolonged period of time. A receiver treated with a water solution of the same and subjected to the action of an electrolytic current gives purple-blue records having a background stable to light.

Example VII The procedure is the same as in Example VI except that for the sodium naphthionate there are used .06 gram mol of 4.4'-diamino-diphenyl- 3.3'-disulfonic acid and .5 gram mol of sodium nitrite.

Example VIII .02 gram mol of chromotropic acid is ground in a ball mill with .02 gram mol of morpholine. The resulting product is dried at a temperature of about 65 C. The product, which is the monomorpholinium salt of chromotropic acid, may be substituted for the di-salt of Example 1.

Example IX .02 gram mol of l-hydroxy-naphthalene-3.6- disulfonic acid and .02 gram mol of morpholine are treated in a ball mill to effect a thorough mixing of the reagents. The product when dried at a temperature of 70 C. may be used in lieu of the morpholine treated salt of Example I. Said product is the mono-morpholinium salt of 1- hydroxy-naphthalene-3.6-disulfonic acid.

The carrier which is treated'with a solution of the above dry mixes may be paper, a fabric or the like. occurs only at the anode, which means that the image record appears on only one surface of the receiver. The image will of course vary in'intensity, depending upon the impulses which are applied to the electrodes.

During electrolysis, dyestuff formation- Various modifications oi the invention will 06- our to persons skilled in the art and I therefore do not intend to be limited in the patent granted except as required by the prior art and the appended claims.

I claim:

1. A storage-stable dry mix for use in producing electrolytic recording solutions containing as its essential components a source of diazonium ions capable of yielding a diazonium compound under the influence of an electrolytic recording current, a water soluble inorganic salt as the electrolyte in an amount to insure passage of the electrolytic recording current through such solution, a sufiicient quantity of a naphthol sulfonic acid, a sulfonic acid group of which has been neutralized by morpholine to couple with the diazonium compound when formed to produce an azo dye, said composition when dissolved in water having a pH on the alkaline side.

2. A storage-stable dry mix for use in producing electrolytic recording solutions comprising as its essential components a diazotizable amine, a sufiicient quantity of an ionizable nitrite to produce the nitrite ions necessary for diazotization of said amine under the influence of an electrolytic recording current, a water soluble inorganic salt as an electrolyte in an amount to insure passage or the electrolytic recording current, and a sufilcient quantity of a naphthol sulfonie acid in which at least one of the sulfonic acid groups is neutralized by morpholine to couple with the diazonium compound when formed to produce an azo dye, said composition when dissolved in water having a pH on the alkaline side.

3. A storage-stable dry mix for producing electrolytic recording solutions containing as its essential components a diazo amino compound capable of yielding a diazoniumcompound under the influence of an electrolytic recording current, a water soluble inorganic salt as the electrolyte in an amount to insure passage of the electrolytic recording current and a sufficient quantity of a naphthol sulfonic acid in which at least one sulfonic acid group is neutralized by morpholine to couple with the diazonium compound when formed to produce an azo dye, said composition when dissolved in water having a pH on the alkaline side.

4. A storage-stable dry mix for producing electrolytic recording solutions containing as its essential components a source of diazonium ions capable of yielding a diazonium compound under the influence of'an electrolytic recording current, a water soluble inorganic salt as the electrolyte in an amount to insure passage of the electrolytic recording current, and a sufiicient quantity of a naphthol polysulfonic acid at least one sulfonic acid group of which is neutralized by morpholine to couple with said diazonium compound when formed to produce an azo dye, said composition when dissolved in water having a pH on the alkaline side.

5. A storage-stable dry mix for producing electrolytic recording solutions containing as its essential components a diazotizable amine, a suificient quantity of an ionizable nitrite to produce the nitrite ions necessary to diazotize said amine under the influence of the electrolytic recording current, a water soluble inorganic salt as the electrolyte in an amount to insure passage of the electrolytic recording current and a suflicient quantity of a naphthol polysulfonic acid in which at least one of the sulfonic acidgroups is neutralized by morpholine to couple with the diazonium compound when formed to produce an azo dye, said composition when dissolved in water having a pH on the alkaline side.

6. A storage-stable dry mix for producing electrolytic recording solutions containing as its essential components a diazo amino compound capable of yielding a diazonium compound under the influence of an electrolytic recording current, a water soluble inorganic salt as the electrolyte in an amount to insure passage of the electrolytic recording current, and a sufiicient quantity of a naphthol polysulfonic acid in which at least one sulfonic acid group is neutralized by morpholine to couple with said diazonium compound when formed to produce an azo dye, said composition when dissolved in water having a pH on the alkaline side.

7. A storage-stable dry mix for producing electrolytic recording solutions containing as its essential components, sodium naphthionate, a sufficient quantity of sodium nitrite to produce the nitrite ions necessary for diazotization of said sodium naphthionate under the influence of an electrolytic recording current, a water soluble inorganic alkali metal salt as the electrolyte in an amount to insure passage of the electrolytic recording current and a suflicient quantity of a morpholinium salt of chromotropic acid to couple with the diazonium compound when formed to produce an azo dye, said composition when dissolved in water having a pH on the alkaline side.

8. A storage-stable dry mix for producing electrolytic recording solutions containing as its essential components the diazo amino compound of diazotized naphthionic acid and diethanolamine capable of yielding a diazonium compound under the influence of an electrolytic recording current, a water soluble inorganic salt as the electrolyte in an amount to insure passage of the electrolytic recording current, and a sufiicient quantity of a morpholinium salt of chromotropic acid to couple with the diazonium compound when formed to produce an azo dye, said composition when dissolved in water having a pH on the alkaline side.

9. The composition as defined in claim wherein the morpholine salt is the di-salt of chromotropic acid.

10. The process of producing color images on a moving fibrous receiver by the electrolytic facsimile recording method which comprises impregnating the receiver with an alkaline solution of a source of diazonium ions capable of yielding a diazonium compound under the influence of the electrolytic recording current, a water soluble inorganic salt as the electrolyte in an amount to insure passage of the electrolytic recording current and a suificient quantity of a naphthol sulfonic acid at least one sulfonic acid group of which is neutralized by morpholine to couple with the diazonium compound when formed to produce an azo dye and subjecting the so treated receiver to the action of an electrolytic recording current.

11. The process as defined in claim 10 wherein said source of diazonium ions is a diozotizable amine and a nitrite.

12. The process of producing color images on a moving fibrous receiver by the electrolytic facsimile recording method which comprises impregnating the receiver with an alkaline solution of diazotized naphthionic acid stabilized with diethanolamine, capable of yielding a diazonium compound under the influence of an electrolytic recording current, sodium chloride as the electrolyte in an amount to insure passage of the electrolytic recording current and a sufiicient quantity of a morpholinium salt of chromotropic acid to couple with the diazonium compound when formed to produce an azo dye and subjecting the so treated receiver to the action of an electrolytic recording current.

13. A fibrous sheet material impregnated with an aqueous solution of the composition of claim 1.

14. A fibrous sheet material impregnated with an equeous solution of the composition of claim 2.

15. A fibrous sheet material impregnated with an aqueous solution of the composition of claim 3.

16. A fibrous sheet material impregnated with an aqueous solution of the composition of claim 7.

17. A fibrous sheet material impregnated with an aqueous solution of the composition of claim 8.

HAROLD G. GREIG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,135,964 Dahlen Nov. 28, 1938 2,306,471 Solomon Dec. 29,- 1942 OTHER REFERENCES The Aromatic Diazo-Compounds and Their Technical Applications, by K. H. Saunders, published by Edward Arnold and 00., London 1936, pages 108, 109, 110. 

